1. Field of the Invention
The present invention relates to phosphorous-containing aluminum carboxylate salt flame retardants for use in polymer articles of manufacture and polymer articles of manufacture comprising such flame retardants compounded with a polymer.
2. Introduction
Halogenated flame retardants are well known and well established in the industry for imparting flame retardant properties to polymer materials. However, there is a desire to move away from halogenated materials and identify non-halogenated flame retardants that are suitable for use in compounding with polymer resins. Popular non-halogenated flame retardants for use in compounding with polymer resins are phosphorous-containing flame retardants.
Some applications for polymer articles require use of a flame retardant that is not only a non-halogen flame retardant, but that is insoluble in the polymer. Phosphorous components such as triphenyl phosphate tend to be soluble in polymer resins. When the phosphorous containing flame retardant is soluble in the polymer resin with which it is compounded, the flame retardant lowers the softening temperature of the polymer resin, that is, it plasticizes the polymer resin. A polymer compounded with a plasticizer generally has a lower thermal dimensional stability, which means it is limited for use to applications at lower temperatures than a similar non-plasticized polymer. Therefore, it is desirable to not only identify a non-halogenated flame retardant suitable for use in compounding with a polymer, but one that is not soluble in the polymer.
A number of options are available for phosphorous-containing non-halogenated flame retardant additives that are insoluble in polymer resin.
WO2011/163207A2 discloses a method for making aluminum methyl methyl phosphonate (AMMP) in particulate form for use as a flame retardant additive.
US2007/0149659A1 discloses a salt of a phosphinic acid having particle sizes of 0.5-10 microns for use as a flame retardant in methacrylic compositions.
It would advance the art to identify an alternative insoluble non-halogenated flame retardant that is suitable for use in increasing flame retardant properties of polymer resin. It would be a particularly desirable advancement if the alternative insoluble non-halogenated flame retardant was a more effective flame retardant than AMMP and/or phosphinic acid salts.